There are two answers to your question. Some rises are from true bulbs
(beardless) like the Dutch iris and others from rhizomes which
have families that are bearded and others that are beardless. Bob's
answer of the bulb irises being the most grown using $ as the measuring is
accurate if bulb type irises are included in the question. If your question is
limited to rhizome type irises, then tall bearded are about a 9 to 1 favorite
over all other rhizome type irises. Tall bearded have a greater growing range,
colors and patterns than the beardless rhizome types. So far I have
grown almost all of the various kinds. They are all nice and have different
characteristics for different situations of garden and climate.